Casting molds used to produce ancient coins in Northern Song Dynasty (960-1127) are seen in Yuncheng city, North China’s Shanxi province. Two enthusiasts of the city's salt lake culture discovered the molds while taking photographs of birds there. Yuncheng’s salt lake, known as "China's Dead Sea,” has a history as a source of salt crystals for over 4,000 years. (Photo/CFP)
